Further studies of the norditerpene (+)-harringtonolide isolated from Cephalotaxus harringtonia var. drupacea: absolute configuration, cytotoxic and antifungal activities.

Harringtonolide (= hainanolide) is a complex polycyclic fused norditerpene isolated from CEPHALOTAXUS HARRINGTONIA var. DRUPACEA. In spite of its appealing biological properties - we measured an IC (50) of 43 nM on KB cells and a significant antifungal activity - its absolute configuration has not yet been firmly established. This was done herein using X-ray anomalous scattering after bromination of the tropone ring, unambiguously giving the stereochemistry 5 R,6 R,7 S,13 S,14 S,15 R,16 R. Detailed IN VITRO biological measurements are provided.